add codegen subdirectories to mypy-strict.ini (#56523)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/56523
Test Plan: Imported from OSS
Reviewed By: malfet, samestep
Differential Revision: D27890855
Pulled By: bdhirsh
fbshipit-source-id: 78cd725bcf534b8410bdfaf93d2eb681e8a56ff7
